设f(x)连续函数，则=（ ）。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/d61df8d810544f27ada3ecb86c2d853a.png
举一反三
- 图示单元体应力状态，沿x方向的线应变εx可表示为（ ）。 <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/9fdd7efe625f4047bb61ef38f5aea871.png" /> A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/5da2d36f7ef84cbc8396b1e27b775bf4.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/164a3d85fdb6462696d83d62b92b2435.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/9e37e58e1c12442e8e018c0af637dfdf.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/41fd81417e5f47bea1db35fed7c2c44e.png" />
- 已知f(t)↔F(w)，则下列说法正确的是（） A: tf(t)↔wF(w) B: F(t)↔f(w) C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/e987a05c70d3455bad2fbdef6ce1fc1d.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/92f68075a5ff43708660199e4eed9415.png" />
- 拉普拉斯（Laplace）方程的表达式为（ ）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/26731bcad75f41389448b29292940653.jpg" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/40e7e55a72ee44f59b45d20c84ebe3a6.jpg" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/c65a79ea4d754174b99f34020d6e1735.jpg" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/139e8d3dc37941549e7b6b1731243172.jpg" />
- 下列四种产品中，（）属于主体附加。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/7de8bb1790ee4eccbc8fe23d663cb293.JPG" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/9f76d9ce04cb4729b4739bdd64d5917b.JPG" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/b4d8b1ab0b9c4f5e8d165f7afd487e00.JPG" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/4862f4e33e114c63bcfa3ebf5c112cba.JPG" />
- 下列四种产品中，（）属于同类组合。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/ee5cc627e4a243ea8fc5025d6736de65.JPG" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/95326815255349e7bb11324655294818.JPG" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/07ebf5a3e62b47d2be75f2574f2bee3e.JPG" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/a46447046f5340d8977c1ffed9a70772.JPG" />